ABC box

[JustPaus_88TSi]

Seems i've been talking about this type of sub box since I learned about it in 99...

Here's a few pics I finally found..

 

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_7.jpg

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_19_full.jpg

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_21_full.jpg

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_17_full.jpg

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_1_full.jpg

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_10_full.jpg

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_11_full.jpg

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_12_full.jpg

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_13_full.jpg

[JustPaus_88TSi]

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_14_full.jpg

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_5_full.jpg

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_30_full.jpg

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_96_full.jpg

I'll end it with a 6 foot subwoofer ;D

[starquestPilot]

That's GREAT!  You had me hooked until I saw the last picture - then I was ROTFLMAO!

 

Mike

[raytech]

That design is very interesting. What are the mathematics behind it. It obviously has alot to do with wave length versus chamber size and vent size into the other acustic chamber. the measurements must be ultra critical. even more so than a regular bandpass, or isobaric.

 

You have me interested in the gains of this particular configuration.

[emann420]

Hey guys, I'm going to go out on a limb here but it looks like a sixth-order band pass to me.  I believe the idea behind it is that the front ported box unloads into the seccound ported box therefore allowing a second but in phase wave to come frome the back side of the cone though both ports.  The advantage of this box is exteme efficiency in a wider range of frequency than a standard fourth-order box.  The design is basically the driver in a ported box that is extended to another ported box with half the air space with a port connecting the two boxes.  The trick is to tune the first box to be compatible with the second to make the box tune to either one octive or tw octives apart, or for that mater three, or four.  The box design goes as follows: The main box is as big as half of the internal air space of the second box with an equal length port that connects the two.  The speaker acts like a sealed box speaker up untill the tuning frequency of the port, then after that it acts like a sub in a ported box until the frequnceies drop below the tuning frequency of the ported box and the transfer to the other box connected with an equal lenght port to a box that is half of the size of the original box minus driver displacement and port displascement.  It ends up being a rather large box that is not for the enthusiast but more fore the hard core audiophile.

 

E-Mann

[JustPaus_88TSi]

.   The box design goes as follows: The main box is as big as half of the internal air space of the second box with an equal length port that connects the two.  The speaker acts like a sealed box speaker up untill the tuning frequency of the port, then after that it acts like a sub in a ported box until the frequnceies drop below the tuning frequency of the ported box and the transfer to the other box connected with an equal lenght port to a box that is half of the size of the original box minus driver displacement and port displascement.  It ends up being a rather large box that is not for the enthusiast but more fore the hard core audiophile.

 

E-Mann

 

Absolutely true.. Especially the last sentence.. The total volume of the box needs to be at the sub's highest allowed ported box size, stated by the manufacturer in Cu.Ft.. It could end up being fairly big(4cu.ft) or really huge(15+cu.ft.)..That all depends on the sub's specs.. If it's a SPL oriented sub, then your regular ported boxs can be as large as 8-10, sometimes 12 cubic feet, with large port volume..Like 150-200 square inches..

The reason I like this type of box, has alot to do with my music choice and stereo equipment. It's the most versatile box design i've ever heard.. It's perfect for me, but that's just me.. Extreme low freq's like 28-32hz with 3000+watts on a quad-coil 18, in this type of box is actually kinda unbearable.. Most people don't take bass to the level that I like, but that's cool.. I've gone through all kinds of different systems, 10's, 12's, 15's, and 18's.. Ported, sealed boxes..Bandpass aswell, although I have hated every bandpass box i've heard, unless it had alot of subs in it(8-12etc..).. I'm in it for clean, low freq. bass..

Audiophile defines it very well..  

[raytech]

You can't ask for a cleaner low freq system than a bandpass. You'll never hear distortion. It is not possible to hear distortion in a properly tuned band pass. The speaker will blow first, this system seems kind of odd. I see the theory, but it has a problem to me. certain speakers are good for sealed and others for ported. Usualy not both at the same response levels.

 

I would be interested in knowing the thiele small parameters of the speakers used and also the math behind this configuration.

[JustPaus_88TSi]

Let me reiterate a bit.. When I think of different box's and such, i'm throwing in the whole system's factors into my plans.. Aswell as the actual car that's going to be used.. The car/install is the biggest part of it.. I know exactly what you're talking about with the bandpass box, and not being able to hear much distortion.. My friend just had a prefab'd bandpass box in his car with two 12's.. I didn't install it, nor did I pick out any of the equipment(Guess who's doing it all now ).. I took a sub out, to find that the whole surround had become unglued, it was about 20% connected(surround to the basket).. This thing was just flopping around like nobody's business, lol but it didn't sound bad..  Of course you're not going to hear it much, there's plexi inbetween you and the subs..

 

The name of the game with Sub's is to move and compress air.. With a bandpass type box, it isn't going to do the best job..  Again, it's going to come down to personal taste..  I like single sub setup's.. 18 in a large ported box with at least 2500 watts on it.. Real watts too, bench tested etc...

The other thing I like is the low, rumbley, rolling bass.. So the ABC box is just what I need..  I'd just as well go with a huge ported box with a port big enough for me to sit in(seriously), but I could care less about SPL comp's and being loud.. I've done that, and it's not my fortay...

 

If someone is really into getting THE best box, they'll need to measure their car and tune accordingly..

 

I will say that, THE BEST box design is a egg shape.. I can't get into all the specific's about why this and how that. But if someone really, really wants to know, then i'll ask the people who told me about such box shapes..Mostly highend competitors with insane equipment metering from 149-172DB, with 2000-20,000watts.. All I know is i've tried every single type of box that's out there, with exception for the egg shaped box and tranny tunnel enclosure's...

Sealed-.75-5 cubic feet(10,12,15,18)

Ported-1.25-12.5 cubic feet(12,15,18)

Horn-4.5-8 cubic feet(15,18)

Bandpass-.75+3.25 for a single sub setup(15,18)

Freeair-(12,15)

ABC-9-12 cubic feet(18)

Passive crossover(uses a type of membrane) etc...Even boxes with adjustable ports, for different frequency peaks etc..

 

But like I said before, it all depends on the type of sub used.. And honestly, to me.. The amount of power going to the sub is very important.. I wouldn't suggest for someone to build a 10 cubic foot ABC box for a Pyramid/Crunch/Boss 15 or anything that isn't capable of handling at least 1200-1500 watts.. Just like I wouldn't suggest building this type of box if you only have 300 watts etc..

 

This box is perfect for me, i'll never build a different type of box(for my car)..

 

But, if someone want's some serious technical answers..I'll ask the people who introduced the box to me..

[pure_insanity]

just paus,  i knew you was my kind of person.  i played audiophile for a while but left it alone to play with other stuff(hydraulics).   a buddy of mine got ahold of a 27" ramsdell, from some sort of big a** concert speaker.  i dont remember what the amp was he used but it was supposed to be like 1800 watts high current.  stuffed all this into the extended cab section of a mazda truck.   talk about bass, it wasnt long before the windshield was leaking  and the doors didnt fit right. bolts was loose all over the place. some kid offered him way too much money for it and it was gone but we had fun with it while he had it.  id love to have known some db #s or spl.

[raytech]

I would like some technical answers. Sound is all about numbers and how those numbers relate to their surroundings. I design my own enclosures, but I do it by math and then I adjust it for fitment. If you are building these boxes, where are you getting the dimensions from? Are they being provided to you? Do you calculate yourself?

 

I would like to know these things so that I may try this out myself.

 

But I am not willing to try something that I cannot myself calculate.

[MikeMeyerhoff]

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_5_full.jpg

 

Is this one a tuned length design?  

 

Its nice to see DIYers still doing this...  most commercial products just use electronics now adays and don't end up nearly as effecient.

 

Nice pics!

mm

[JustPaus_88TSi]

I would like some technical answers. Sound is all about numbers and how those numbers relate to their surroundings. I design my own enclosures, but I do it by math and then I adjust it for fitment. If you are building these boxes, where are you getting the dimensions from? Are they being provided to you? Do you calculate yourself?

 

I would like to know these things so that I may try this out myself.

 

But I am not willing to try something that I cannot myself calculate.

 

When it comes to this type of box, I have only made one.. I also create box's just like you do, with math.. Is there any other way? ;D

The dimensions thing is dependant on the Sub, and it's maximum ported box size..

The only thing I didn't do myself was the port tuning.. I have no idea how to tune three ports..

 

I'll try and get someone to answer the port calculation theory..It's not like normal ported boxes.. I think someone told me that even though there is 3 ports, you actually tune it using 2 ports in mind.. However, all the ports MUST be the same length.. Something like that.. It's been 3 years since I made it...

 

I'll find out though..

[raytech]

That would be appreciated.

[JustPaus_88TSi]

http://memimage.cardomain.com/member_images/12/web/192000-192999/192579_5_full.jpg

 

Is this one a tuned length design?  

 

Its nice to see DIYers still doing this...  most commercial products just use electronics now adays and don't end up nearly as effecient.

 

Nice pics!

mm

 

If it has ports, it's a tuned length design.. The only thing with these is that they have 3 ports/2 chambers.. With this box though, the ports aren't conventional PVP piping.. This is what is called Slot porting(this one actually is square, usually they'll be rectangular).. It's just away to get more squared inches into the port.. Thus(if you have the right amount of power) being louder, vs. a small sq. in port.. It allows more air to be moved into the cabin of the vehicle, compressing more air--and effectively being louder(SPL)db etc..That's just the port type though. The box's design is important here.. Like E-mann was saying, it has tuned chambers.. Much more versatility this way..

 

edit: Oops ..they're not square.. But most of the slot ports i've seen are like 4''x14'' etc.. Kinda slim..

I'm looking at my dad's old set of speakers right now.. They're CV's from about 1973-4ish..  The box's have a huge slot port on the bottom of the backside.. I think they're mohagany actually..

[JustPaus_88TSi]

''ABC is an Tri-Tuned Ported enclosure... Take 6ft^3 volume figure out the port for 30hz using two ports... Now split the volume up into 4ft^3 and 2ft^3 and make a 3rd port exactly the same as the first two and use it to connect the two volumes internally... This box also requires precision cuts to get the volume of each chamber correct and ports all the same...''

 

This is what I was told about 4.5 years ago..

It's so simple now that I think about it.. I've been neck deep in learning about SQ's, I tend to forget other things, even though I like them ..

 

If you want to get into the nitty gritty, take the port area's into consideration when you are deciding on total "Net" volume.. Ports take up space inside of the box ..

 

From what I just glanced at, the smaller chamber will be 1 octave higher than the larger side..If it's built right..

[raytech]

Where does the 6 cu. ft. come from?

[JustPaus_88TSi]

That's just an example.. Since 6 works out real good with the 1/3 and 2/3 sections..

 

Works out good like:

3cu.ft= 1cu.ft section/2cu.ft section

6cu.ft= 2cu.ft section/4cu.ft section

9cu.ft= 3cu.ft/6cu.ft

12cu.ft= 4cu.ft/8cu.ft

etc...

Remember there must be two sections, one being twice the size of the first..

It's just an easier way of telling people who don't grasp the concept at first..

 

4.5cu.ft= 1.5cu.ft/3cu.ft

7.5cu.ft= 2.5cu.ft/5cu.ft

 

The beauty of it is, you do regular port tuning to figure out the tuning..the box's design does the rest(raising 1 octave etc..)

 

I suggest using PVC pipe or anything round.. When you make your ports square, and you use the actual box's side for 1/2 of the port, you have to figure out the 'port end correction'.. With ports built like that, the wall of the box actually lenghtens the port's effective size(if you cut it to 6 inches long, it'll act like its a 8-10 inch long port), effectively raising/lowering your tuning..  Just incase someone wants to know , to figure out the port end correction.. Take the width of your port, and subtract that from the ports length..

 

So, if you have a port that's 10''h/4''w/16''d... Take the 4'' and subtract that from 16''..   So, you end up with 10h/4w/12d for the port...

[raytech]

So if I had a 10 inch sub with

Vas=2.1

Qts=.41

fs=24

 

Then the ideal ported box would be 2.44 cu.ft.  with a port diam of 3" and length of 13.25 inches.

 

So I would need another chamber of 4.88 cu.ft and a connecting port of 13.25 inches and an external vent in that chamber of 13.25 inches.

 

I would be looking at a total box volume of 7.32 cu.ft.

 

Or would it be the other way. The second chamber would have a volume of 1.22 cu.ft and a connecting vent of 13.25 inches and external vent of 13.25 inches. With a total volume of 6.1 cu.ft.

[JustPaus_88TSi]

How are you arriving at those numbers using VAS,QTS,FS?

 

Also, what are you trying to tune your box to? What Hz?

http://audiobahninc.com/tech/calculators/portlengthcalc.htm

I just plugged in 7.88cu/ft and tuned to 35hz, it was like 1.75'' long for the port..30hz was 3.18'' long...

 

Remember you tune the whole box, 'net' volume using 2 ports..

Can you get larger pvp pipe?  Even going with 4inch piping, it makes the tuning for 35hz 4.09'' long, and 30hz is 6.62''...  I'd try for at least 5'' PVP pipe..

 

What kind of sub do you have?

[JustPaus_88TSi]

Wait...Scratch everything I just said..

You have one 10..

The MAX ported box size is 2.44?

 

Then 2.44 is your 'net' or whole volume of the box..

2/3 of 2.44 is 1.6266666 (big chamber)

1/3 of 2.44 is 0.8133333 (small chamber)

 

Now, you plug 2.44 into the equation...

For 35hz, using a 3'' port..It'll be 10.55'' long

For 30hz, is 15.15'' long..

 

It is a 10 though, so maybe a 38-42hz tune would be better...

You can start with a long port and take some away little by little.. That way, it'll start at a lower Hz, and work it's way up... You'll see what I mean, just plug in numbers into that calculator...

[raytech]

Where do you come up with max ported size of a box just using the speaker size?

 

The numbers I gave were for a flat response out of a ten inch speaker with the thiele small parameters I gave. Why do you tune to 30-35 hz?

 

I guess the whole problem that I am having with this box is the simplicity in which it is conveyed. Is it really this simple? All about thirds and equal port length.

 

This is a screen shot of the program used to calc the box with all of the numbers.

 

http://f1.pg.photos.yahoo.com/ph/raytech77...p;.dnm=1fbf.jpg

[JustPaus_88TSi]

I can't say what the biggest ported box size is for your speaker.. But usually when you get a sub, it'll have the max sizes for sealed and ported with a info sheet provided..

 

Also, that pic you linked.. You used 1 port in the calculations.. Switch it to 2...

 

And yes, it really is that simple.. The box design itself does all the work, assuming you can build it to a nearly perfect 1/3 and 2/3 split(chambers)...

 

I was throwing in 30 and 35hz just for an example.. In that info sheet I just talked about, it'll have the lowest Hz that the sub can reproduce.. You can tune a tiny bit below that if you like(2-3hz below)...

 

I have to get back up to par with my value's..Vas. QTS. BL. etc...  I totally forgot everything that has to do with them :...

 

Remember:

When tuning the box, forget that there's two chambers and forget that there's actually 3 ports.. Plug in the total(net) volume, and tune it using 2 ports.. Then just make the 3rd port the same length as the first two...

[88BlueTSiquest]

Also, that pic you linked.. You used 1 port in the calculations.. Switch it to 2...

 

Whether it's one port or two, the equation would still be the same, as the port displacement will be identical. Instead of 1 port at 13 ¼" it would be a pair of ports at 6 5/8" or there abouts.

[JustPaus_88TSi]

Very true..  But, when he thinks it's 13", he'll make all 3 ports 13''.. instead of the correct 6'' for all 3...  This box must be built dead-on-balls accurate for it to work like it's intended to..

[raytech]

When you tune using multiple ports you get a different cross sectional area of port volume. You can't just add a second port and divide length by 2. That just doesn't work. I would also like to know how the caluculator on audiobahn works without having any speaker specifications. It doesn't take into consideratio the speakers Qes Qms And Qts as well as the speakers FS. That just seems like buying a prefabbed bandpass box and throwing in any old speaker.

 

TotalPortDiameter= SQRT(port1^2 +port2^2)

 

Plus it was mentioned to increase port diameter, but this would require longer ports.